Inflatable bag aerial



Nov. 30, 1965 D. M. BROWN 3,221,333

INFLATABLE BAG AERIAL Filed March 5, 1962 FIGZ INVENT OR mm, #W 4 m q ATTORNEY;

United States Patent "ice 3,221,333 INFLATABLE BAG AERIAL Desmond Macartney Brown, Hounslow, Middlesex, England, assignor to Ultra Electronics Limited, London, England, a corporation of Great Britain Filed Mar. 5, 1962, Ser. No. 177,529 1 Claim. (Cl. 343-872) This invention relates to an inflatable bag aerial which may be rolled or folded when not in use, such as may be used, for example, in a parachute pack for a crash position indicator radio beacon, in meteorological balloons, and in the radio kit of a man engaged in active service.

In accordance with the invention, a radio aerial is provided that comprises two webs of wire so supported by a flexible bag that when the bag is inflated, the two webs of wire lie in substantially parallel spaced apart planes to provide a tuned radio aerial operating on the capacity plate principle. Each web of wire may be directly secured, as by sewing, to a flexible sheet of nonelectrically conductive material. The two sheets may be secured to the interior of the inflatable bag, or they may form part of the exterior walls of the inflatable bag.

The following description relates to the accompanying drawings and showing by way of example only two embodiments of the invention.

In the drawings:

FIGURE 1 is a view of one web of wire supported on a flexibble sheet of nonelectrically conductive material;

FIGURE 2 is a section through an inflated bag and showing the two webs of wire therein in a parallel spaced apart condition, each web being on a sheet of nonelectrically conductive material; and

FIGURE 3 is a section through an inflated bag, of which the walls themselves carry the two webs of wire in a parallel spaced apart condition.

As shown in FIGURE 1, a circular sheet 11 of plastic material has an aerial in the form of a framework of wire 12 sewn upon one surface. The wire used for the web 12 may be of the type used for telephone headset cable. All joints and crossings of the web or frame- 3,221,333 Patented Nov. 30, 1965 work of wire are soldered together. at its centre 13.

As shown in FIGURE 2, the circular sheets 11 are secured to the interior of an inflatable bag 14. As shown, there are two such sheets 11, each with its aerial web 12, so that the two webs together co-operate to form the well-known capacity plate aerial. Being inflated as shown, the bag 14 has the shape of an oblate spheroid.

In FIGURE 3, on the other hand, two circular sheets 11 of nonelectrically conductive material are used to form two parallel spaced apart and opposite 'faces of an inflatable bag 15, each sheet 11 carrying an aerial web.

The dimensions of the webs 12 and the spacing between the two webs, is, of course, determined by the desired operating frequency. It has been shown that for a reasonable size of aerial, the invention has been most useful over a band of frequency of mc./s. to 400 mc./s.

What is claimed is:

A radio antenna comprising an inflatable flexible bag in the shape of an oblate spheroid when inflated, including when inflated, a pair of spaced parallel insulating planar surfaces connected to a medial portion of said spheroid; a first conductive antenna element mounted on one of said planar surfaces and a second conductive antenna element mounted on the other of said planar surfaces, said elements being mounted in opposing relation in such a manner as to define a capacitive plate antenna when said bag is inflated.

The aerial is fed References Cited by the Examiner UNITED STATES PATENTS 2,814,038 11/ 1957 Miller 343-872 2,888,675 5/1959 Pratt et al 343-880 2,996,212 8/1961 OSullivan 343-18 3,047,860 7/19612 Swallow et al 343-915 3,056,131 9/ 1962 McCreary 343-872 3,138,798 6/1964 Greenwood 343-18 FOREIGN PATENTS 758,090 9/ 1956 Great Britain.

HERMAN KARL SAALBACH, Primary Examiner. 

